Elastic-fluid turbine



Feb. 17, 1925.

G. B. WA RFEEN ELASTIC FLUID TURBINE Original Filed Dec. 22, 1925 11 lm m if mw. t GDMMLH mm m 1 H 6 Patented Feb. 17, 192.5.

umreo STATES PATIENT ornce:

GLENN B. WARREN, OF SCHENECTADY, NEW YORK, ASSIGNOB TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ELASTIC-FLUID TURBINE.

Original application filed December 22, 1928, Serial No. 682,325. Divided and this application filed July 21, 1924. Serial No. 727,149.

To all whom it may concern:

Be it known that I, GLENN B. WARREN, a citizen of the United States, residing at Schenectady, in the county of-Schenectady,

State of New York, have invented certain new and useful Improvements in Elastic- Fluid Turbines, of which the following is a s ecification.

his ap lication is a division of my apm plication gen N 0. 682,325, filed December In building high speed, large capacity turbines, the buckets in the last few stages become quite long which means that there is considerable difference in peripheral s eed between the roots of the buckets and t eir tips; The result is that if in an impulse turbine the central portions of the buckets are running at a speed correct for most efficiently extracting the energy from the elastic fluid isuing from the nozzle then the root ortions are running too slow for highest e ciency and the tip portions are running too fast for highest eificiency.

The object of my invention is to provide an improved means for overcoming this difiiculty due to the difference in speed between the roots and the tips of long buckets whereby better efliciency will be obtained.

In the design of elastic fluid turbines,.it has been found that in order to absorb the same quantity of energy from an elastic fluid a pure reaction combination of nozzle and bucket must run at a speed about 40% greater than a corresponding impulse combination. This means that 1f the root end of a bucket is running at about the right speed to operate as an impulse bucket, the tip end would be running at 'a speed adapted 40 for either total or partial reaction operation.

In carrying out my invention, I take advantage of this fact, and according to my invention in the case of long buckets I so shape the buckets that the fluid passages of the 5 nozzle-bucket combination operate as an impulse combination at their inner or root ends and as either a partial or total reaction combination at their outer or tip ends. According to the embodiment of the invention 5 illustrated in this application, the" above referred to result is accomplished by so constructing the buckets as to give a. smaller exit angle at the radially outer ends or tips of the buckets than at their radially inner ends or roots.

In the drawing Fig. 1 is a radial sectional view through a nozzle-bucket combination indicated at 9. The nozzles receive elastic fluid from bucket row 4 and deliver it to bucket row 5. The construction of the buckets of the nozzle-bucket combination comprising nozzles 7 and buckets 5 is such that the radially inner portion of the combination operates as an impulse combination and changes toward the radially outer portion until at the outer portion the combination operates partially or wholly as a reaction combination the change being gradual from the one to the other. This is accomplished by varying the exit angle of the buckets from their inner ends to their outer ends, the inner ends having an exit angle 1) as indicated in Fig. 2 and the outer ends having an exit angle 6 minus an amount y, as shown in Fig. 3. The nozzle angle a is shown as remaining constant.

Since the outer ends of the buckets'have a certain amount of reaction there is of course, some drop in pressure across them and to limit the leakage I provide suitable packing means as indicated at 10. At 11 is indicated the usual diaphragm packing.

By my invention I. provide a nozzlebucket combination which takes care of the difference in speed between the roots and the tips of the buckets "and thereby gives better efficienc for the combination than has been obtained heretofore. It will be understood that I am using the term nozzle in a. broad sense and intend toinclude thereby any stationary fluid directing element.

What I claim as new and desire to secure partial reaction at the outer portion, the by Letters Patent of the United States, is change being made commen. urate Wivu the 10 In an elastic fluid turbine, a nozzle-bucket difl'erence in speed at which the radially combination wherein the exitangle of the' inner and outer portions of the buckets r0- 5 buckets decreases from the roots of the bucktate.

ets to their tips by an amount such that the In witness whereof, I have hereunto set combination changes from impulse opermy hand this 18th (la of July, 1924. ation at the radially inner portion to at least GLE N B. WARREN. 

